34. The phyla, in order of their increasing complexity beginning from the simple singlecelled form to complex form are like these — protozoa, porifera, cnidaria, platyhelminthes, nematoda, annelida, arthropoda, mollusca, chinodermata, hemichordata and chordata.

35. Symmetricalbody shape means the parts of an animal body are arranged in such a way that it can be cut into two similar halves by one or more planes.

36. Germ layersare the primary layers of cells which differentiate in the animal embryo.